Anything done to the barrel will effect its performance. Not necessarily to the good side or bad side just different than it was before. With that said, a barrel is not normally tested, then unmounted and changes made, re-installed, and then just sent out.

South Pender,
Does all the machining required to make the barrel octagonal not effect the performance of the barrel?
Ken.

That's a reasonable question, and I don't have a definitive answer. It likely depends on the skill of the metalsmith doing the work. I'm hoping that the octagoning of the Sako barrel won't change its performance.

I might add that my gunsmith is a master metalsmith and a member of the American Custom Gunmakers Guild. He does exquisite work and has octagoned some other barrels for me. One he did for a Kimber 82B rimfire project, and another for a Rem. 40XBR rifle in .22BR. Both rifles shot very well after the octagoning. I have two other rifles with octagonal barrels--both Wichita Classics, with the barrel, receiver, and bolt shroud all octagoned and nicely blended. They are good shooters.

Just for fun and because I've been told you guys like pictures, here are some pics of my Kimber 82B .22LR project that my gunsmith built, showing the octagoning and custom scope bases, along with a different treatment of the bottom metal and hinged floorplate. This was an aftermarket custom barrel (can't remember whether it was a Krieger or Lilja) that the gunsmith octagoned for the project. Despite its somewhat light barrel weight, the rifle shoots right along with my heavy-barrel Anschutzes, producing average groups, with the ammo it likes, in the mid-.3s for 5 shots at 50 yards.

After completion of the Sako project, we'll be starting in on an Anschutz 54-action .22WMR project. For that one, my gunsmith has a barrel from Lilja that Dan Lilja octagoned.

I've owned and still own a bunch of Coopers, but won't say how many 'cuz someone might come and carry off my two safes. I'm an unrecoverable Cooperholic.

I think over the years we have had 4 Saubier Postal Shoots. Coopers have been classified for them as "custom".

Of the 4, I won two, both with Varmint Extremes, a 17M4, and a 20VT. I did shoot other Coopers in each, standing well down in the list for the 3 each five shoot groups.

The best group was with one of the "non-winners", an old small barreled 17AH with a Schabnolled (SP) stock and 20 inch barrel, at 0.944" at 100 yards. Ended up with something like a half MOA aggregate for that set.

I've had two Coopers that went back due to really bad barrels, one that would foul so badly that while the first 3 shot group was half MOA or better, by the third group would grow to 4-5".

I had one of the bad reamer 17M4s, a Classic M21. Rob Behr put 2 or three barrels on it that wouldn't make muster. Ended up asking me if he could change the caliber. I agreed and it came back as a 223AI . That summer I killed more ground hogs with it than I had killed in one year with all but one of my other Coopers, a Classic M21 in 223.

I have had two Browning 22s, one Micro Medallion and one Micro Hunter that shoot Hornady 35 gr. Vmaxes into half MOA groups, as well as two Varmint barreled CZs, a 223 and a 17HH that shot in the sub half MOA range, so I'm not a complete Cooper hog.